For many years now Sikorsky has designed and built safe reliable aircraft for our service men and women around the world. The H-60 and other similar aircraft are relatively new helicopters, which Sikorsky and others are constantly improving with respect to features, safety, support equipment, and maintenance. For example, U.S. Pat. No. 5,322,415, which is incorporated by reference herein in its entirety, discloses a pitch actuation restrain device that may be used with the H-60 and other Sikorsky helicopters.
The safety of the H-60 and any other aircraft during operation is highly dependent on proper maintenance. Many maintenance schedules for helicopters require that, at minimum, the spindles be removed from the main rotor hub annually. However, close tolerances between the elastomeric bearing (to which the spindle is secured) and rotor hub make spindle removal and installation very difficult. Many helicopters are four-blade designs, meaning each helicopter includes four spindles each. Using traditional methods, the removal or installation of just one spindle may require two or three maintenance personnel working for 24 hours, for a total of 48-72 man hours.
The traditional methods that maintenance personnel have learned and developed involve inherent risks as a consequence of a desire to minimize aircraft downtime. Maintenance workers often scrape or polish paint and primer off of opposing surfaces of the rotor hub and bearing because of the difficulty of installation of the spindles. Furthermore, maintenance workers often fail to apply sealant between these opposing surfaces and instead apply sealant only to the exterior seam between the bearing and hub. The absence of sealant between the opposing surfaces somewhat mitigates the difficulty of spindle removal, but decreases rotor hub and bearing life due to increased corrosion (which may be a dissimilar metal corrosion depending on materials of construction) between the opposing surfaces of these components.
Maintenance personnel have permanently damaged $130,000 rotor hubs and/or $14,000 elastomeric bearings by attempting to pry the bearing from the rotor hub with a screwdriver, chisel, or other tool. Sometimes personnel use an over head crane at an angle relative to the longitudinal axis of the bearing to provide a means of force in the direction of spindle removal.
Such procedures have proved very dangerous due to the increased likelihood of the spindle assembly, which may weigh in excess of 150 pounds, to swing uncontrollably from the overhead crane once the spindle assembly has become dislodged from the rotor hub.
Accordingly, a need exists for a better tool and method for removing bearings from hubs, and particularly for removing elastomeric bearings from main rotor hubs of various aircraft.